Experiment: Add python_uv hook environments

[j178]

Adds language: python_uv that builds a clean prek-managed virtualenv from a uv project lockfile and selected groups/extras.

Closes #1675

[codecov]

Codecov Report

❌ Patch coverage is 87.21805% with 170 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.09%. Comparing base (d87be90) to head (936415e).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
crates/prek/src/languages/python/python.rs	66.26%	56 Missing ⚠️
crates/prek/src/hook_env.rs	87.36%	36 Missing ⚠️
crates/prek/src/hook.rs	95.27%	17 Missing ⚠️
crates/prek/src/languages/mod.rs	78.18%	12 Missing ⚠️
crates/prek/src/config.rs	68.75%	10 Missing ⚠️
crates/prek/src/cli/cache_gc.rs	85.24%	9 Missing ⚠️
crates/prek/src/languages/rust/version.rs	90.69%	4 Missing ⚠️
crates/prek/src/languages/dart.rs	72.72%	3 Missing ⚠️
crates/prek/src/languages/version.rs	76.92%	3 Missing ⚠️
crates/prek/src/store.rs	25.00%	3 Missing ⚠️
... and 15 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2058      +/-   ##
==========================================
- Coverage   92.32%   92.09%   -0.24%     
==========================================
  Files         119      120       +1     
  Lines       24429    25111     +682     
==========================================
+ Hits        22555    23125     +570     
- Misses       1874     1986     +112     

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[prek-ci-bot]

📦 Cargo Bloat Comparison

Binary size change: +0.77% (26.1 MiB → 26.3 MiB)

Expand for cargo-bloat output

Head Branch Results

 File  .text     Size             Crate Name
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_39_1_aes_gcm_encrypt_avx512
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_39_1_aes_gcm_decrypt_avx512
 0.3%   0.7%  89.1KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.6%  82.3KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.6%  74.4KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.5%  63.0KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.4%  53.3KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.3%  43.0KiB              prek prek::cli::run::run::run::{{closure}}
 0.1%   0.3%  36.0KiB              prek prek::run::{{closure}}
 0.1%   0.3%  33.1KiB             prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  32.0KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::Config>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2%  29.1KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble_alt
 0.1%   0.2%  27.6KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble
 0.1%   0.2%  25.7KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  24.6KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2%  22.5KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  22.3KiB         [Unknown] Lp384_montjscalarmul_alt_p384_montjadd
 0.1%   0.2%  21.5KiB      clap_builder clap_builder::parser::parser::Parser::get_matches_with
41.7%  86.5%  11.0MiB                   And 24079 smaller methods. Use -n N to show more.
48.2% 100.0%  12.7MiB                   .text section size, the file size is 26.3MiB

Base Branch Results

 File  .text     Size             Crate Name
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_39_1_aes_gcm_encrypt_avx512
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_39_1_aes_gcm_decrypt_avx512
 0.3%   0.7%  91.7KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.6%  83.6KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.5%  65.4KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.5%  60.3KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  53.3KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.4%  48.8KiB              prek prek::run::{{closure}}
 0.2%   0.3%  43.8KiB              prek prek::cli::run::run::run::{{closure}}
 0.1%   0.3%  32.5KiB             prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  32.0KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::Config>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2%  28.3KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble_alt
 0.1%   0.2%  27.6KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble
 0.1%   0.2%  26.4KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  24.5KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2%  23.5KiB             prek? <prek::cli::Command as clap_builder::derive::FromArgMatches>::from_arg_matches_mut
 0.1%   0.2%  22.5KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  22.3KiB         [Unknown] Lp384_montjscalarmul_alt_p384_montjadd
41.6%  86.3%  10.9MiB                   And 23891 smaller methods. Use -n N to show more.
48.1% 100.0%  12.6MiB                   .text section size, the file size is 26.1MiB

[prek-ci-bot]

⚡️ Hyperfine Benchmarks

Summary: 0 regressions, 0 improvements above the 10% threshold.

Environment

• OS: Linux 6.17.0-1010-azure
• CPU: 4 cores
• prek version: prek 0.3.13+10 (1dc7e7a 2026-05-08)
• Rust version: rustc 1.95.0 (59807616e 2026-04-14)
• Hyperfine version: hyperfine 1.20.0

CLI Commands

Benchmarking basic commands in the main repo:

prek --version

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base --version	2.2 ± 0.1	2.1	2.6	1.00
prek-head --version	2.2 ± 0.1	2.1	2.6	1.00 ± 0.05

prek list

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base list	8.8 ± 0.1	8.6	9.3	1.01 ± 0.02
prek-head list	8.8 ± 0.1	8.5	9.3	1.00

prek validate-config .pre-commit-config.yaml

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base validate-config .pre-commit-config.yaml	3.0 ± 0.0	2.9	3.1	1.00
prek-head validate-config .pre-commit-config.yaml	3.0 ± 0.0	2.9	3.1	1.00 ± 0.02

prek sample-config

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base sample-config	2.5 ± 0.0	2.4	2.6	1.00
prek-head sample-config	2.5 ± 0.0	2.4	2.6	1.01 ± 0.02

Cold vs Warm Runs

Comparing first run (cold) vs subsequent runs (warm cache):

prek run --all-files (cold - no cache)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --all-files	136.3 ± 3.1	131.7	140.1	1.01 ± 0.03
prek-head run --all-files	134.5 ± 2.3	131.2	138.5	1.00

prek run --all-files (warm - with cache)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --all-files	135.8 ± 3.0	130.9	140.4	1.00
prek-head run --all-files	137.2 ± 4.0	132.6	148.5	1.01 ± 0.04

Full Hook Suite

Running the builtin hook suite on the benchmark workspace:

prek run --all-files (full builtin hook suite)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --all-files	134.8 ± 3.3	129.9	142.9	1.00
prek-head run --all-files	135.0 ± 3.3	130.5	146.5	1.00 ± 0.03

Individual Hook Performance

Benchmarking each hook individually on the test repo:

prek run trailing-whitespace --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run trailing-whitespace --all-files	19.5 ± 0.4	18.8	20.6	1.00 ± 0.02
prek-head run trailing-whitespace --all-files	19.5 ± 0.2	19.0	19.8	1.00

prek run end-of-file-fixer --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run end-of-file-fixer --all-files	25.9 ± 2.4	23.0	30.9	1.00 ± 0.13
prek-head run end-of-file-fixer --all-files	25.8 ± 2.3	22.7	29.8	1.00

prek run check-json --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-json --all-files	11.8 ± 0.8	11.0	16.0	1.05 ± 0.08
prek-head run check-json --all-files	11.2 ± 0.3	10.7	11.9	1.00

prek run check-yaml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-yaml --all-files	10.6 ± 0.1	10.4	11.0	1.00
prek-head run check-yaml --all-files	10.7 ± 0.2	10.4	11.2	1.01 ± 0.02

prek run check-toml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-toml --all-files	10.8 ± 0.3	10.3	11.8	1.00 ± 0.04
prek-head run check-toml --all-files	10.8 ± 0.3	10.3	11.4	1.00

prek run check-xml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-xml --all-files	10.8 ± 0.3	10.3	11.3	1.00
prek-head run check-xml --all-files	10.9 ± 0.3	10.4	11.5	1.00 ± 0.04

prek run detect-private-key --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run detect-private-key --all-files	16.8 ± 1.2	14.5	19.9	1.03 ± 0.09
prek-head run detect-private-key --all-files	16.4 ± 0.9	15.2	18.3	1.00

prek run fix-byte-order-marker --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run fix-byte-order-marker --all-files	21.3 ± 1.5	19.1	23.7	1.02 ± 0.10
prek-head run fix-byte-order-marker --all-files	20.9 ± 1.6	18.7	23.7	1.00

Installation Performance

Benchmarking hook installation (fast path hooks skip Python setup):

prek install-hooks (cold - no cache)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base install-hooks	4.5 ± 0.1	4.4	4.5	1.00 ± 0.02
prek-head install-hooks	4.4 ± 0.0	4.4	4.5	1.00

prek install-hooks (warm - with cache)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base install-hooks	4.4 ± 0.1	4.3	4.5	1.00
prek-head install-hooks	4.5 ± 0.1	4.4	4.6	1.01 ± 0.02

File Filtering/Scoping Performance

Testing different file selection modes:

prek run (staged files only)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run	46.2 ± 1.0	44.8	47.9	1.00 ± 0.03
prek-head run	46.0 ± 0.9	44.8	47.8	1.00

prek run --files '*.json' (specific file type)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --files '*.json'	7.9 ± 0.1	7.8	8.2	1.00
prek-head run --files '*.json'	7.9 ± 0.1	7.8	8.2	1.00 ± 0.02

Workspace Discovery & Initialization

Benchmarking hook discovery and initialization overhead:

prek run --dry-run --all-files (measures init overhead)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --dry-run --all-files	10.0 ± 0.1	9.8	10.3	1.01 ± 0.01
prek-head run --dry-run --all-files	10.0 ± 0.1	9.8	10.1	1.00

Meta Hooks Performance

Benchmarking meta hooks separately:

prek run check-hooks-apply --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-hooks-apply --all-files	12.1 ± 0.1	12.0	12.2	1.00 ± 0.01
prek-head run check-hooks-apply --all-files	12.1 ± 0.1	12.0	12.2	1.00

prek run check-useless-excludes --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-useless-excludes --all-files	11.2 ± 0.7	10.5	12.1	1.04 ± 0.06
prek-head run check-useless-excludes --all-files	10.7 ± 0.1	10.6	10.9	1.00

prek run identity --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run identity --all-files	9.6 ± 0.1	9.5	9.7	1.00
prek-head run identity --all-files	9.6 ± 0.1	9.5	9.7	1.00 ± 0.01